K.Lackner*) Max-Planck Institut für Plasmaphysik, D-85748 Garching *) based largely on work of EFDA and the EU DEMO-Working Group Technology and Plasma.

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Presentation on theme: "K.Lackner*) Max-Planck Institut für Plasmaphysik, D-85748 Garching *) based largely on work of EFDA and the EU DEMO-Working Group Technology and Plasma."— Presentation transcript:

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DEMO Working Group following completion of PPCS identical or scalable with high confidence to a first generation power plant (physics technology ABC) physics and technology demands – except availability – similar to PP for DEMO (vs. PP): construction costs rather than COE decisive Pel 1.0 GW

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why hybride mode considered much broader physics base originally considered for pulsed scenarios

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a pulsed DEMO/PP option? known objections pulsed loads need for continuous power output (energy storage requirements) power supplies for rapid restart considered in the expectation: could be designed largely on demonstrated physics base inductive current drive energetically favourable preliminary conclusions (D.Ward et al., based on PROCESS-Code): same physics basis as pulsed device, allows also (more favourable) DC device

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what are the PROs of ITB scenarios? cause: suppression of turbulence in a layer in core (analogy to H-mode) precondition: weak or reversed shear efficient use of bootstrap current (high fraction & distribution) good confinement (H- factor)

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intrinsic problem of ITB scenarios pressure and current profiles (l i..internal inductance) unfavourable for stability only weak barriers, at large radius stable

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confinement confirm assumptions for H and hybrid H-modes establish a scaling for ITB - modes at constant n*, for ITER98(y,2) AUG JET ITER device operating regimes in dimensionless engineering variables dimensionless physics parameters only known after experiment close to Greenwald extrapolation to ITER/DEMO small in β large in ρ*, and particularly! in ν* ρ*ρ* ν*ν* β

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α-particle behaviour (fusion heating) fast particles (due to NBI or ICRH) cause range of resonant interactions, potentially leading to their loss fusion-αs different through isotropy figures of merit: further increase in reactor

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physics/technology interface: plasma wall interaction tritium retention and material erosion full high-Z (tungsten) pfc solution: not in ITER starting configuration to be added – at latest – in phase 2 of operation divertor load issue more severe on DEMO/PP than ITER higher power & power density divertor cooling (He; high duty cycle) not more efficient

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reduction of divertor load by radiation: higher fraction of radiative losses than ITER limits to edge radiation? higher-Z radiators less dilution & Z eff more core losses effect on H-mode pedestal benefit from profile stiffness ITER´s power handling limit, and scaling of problem with size no direct test of solution possible DEMO solution will have to be an extrapolation based on quantitative understanding of carefully chosen experiments on ITER & elsewhere

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DEMO technology: credible 1st generation PP from day1 of DT operation: self-sufficiency of tritium satisfy same high levels of safety and environmental compatibility as demanded in EU PPCS (requiring, among others, use of low activiation materials) aim at a high availability: to produce the neutron fluences needed for testing (during later stage) to extrapolate to an attractive reactor technology requirements similar to 1st generation PP (also not beyond) exception: operational experience in this regard: DEMO an experiment

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Availability: where DEMO is in a different category from ITER remote maintenance and repair segmentation driver of effort compromise between modularity (use testing on ITER) & limited number of elements T. Ihli et al., this conference design target for availability: testing of internal components to 50dpa before start of design of FPP -> availability 33 % second stage: make credible that if operated in a routine fashion an availability >75% could be achieved